How pushing water uphill can solve our renewable energy issuesThe problem with solar energy is that energy is only generated during the day. By using excess solar energy during the day to pump water to a reservoir, it is possible to release that water at night to generate energy when solar energy is not being generated. This day/night cycle can be repeated through the use of an upper and a lower reservoir. It would be interesting to see the cost/benefit ratio for such a system that would cover the needs for a community such as Pioneer Point. In fact, it would be an interesting experiment if funding were available.

When there is excess electricity, water is pumped through a pipe or tunnel, to the upper reservoir. The energy is later recovered by letting the water flow back down again, through a turbine that converts it back into electricity. Efficiencies of 90% in each direction are possible.

In an “off-river” system, the same water circulates in a closed loop between the upper and lower reservoirs, eliminating the need for the facility to be built on a river. The amount of energy stored is proportional both to the elevation difference between the upper and lower reservoirs (typically between 100 and 1000 m), and to the volume of water stored in the upper reservoir.

Of the available electricity storage options, such as batteries and flywheels, pumped hydro is by far the cheapest. It has no standby losses while the water waits in the reservoir, and can reach full power in 30 seconds.

Compressed air energy storageAnother idea is to compress air in a large storage unit (or units) during the day and release it to turn turbines at night. This might and might not be more efficient than the use of batteries.

Compressed air energy storage (CAES) is a way to store energy generated at one time for use at another time using compressed air. At utility scale, energy generated during periods of low energy demand (off-peak) can be released to meet higher demand (peak load) periods.

That seems like a great idea though I guess if you were going to use water from the lake here the pumps would have to deal with corrosion from the brine. I would envision something like solar or wind powered pumps pushing water from the lake to a reservoir and small hydro electric dam in or near the mountains.

PUMPED HYDRO: If this is a closed system, then the real question is How large do the reservoirs need to be to provide energy through the night to a residential area the size of Pioneer Point? Once the water to fill one reservoir is acquired, that water is then recycled forever. If the reservoirs are covered then evaporation will be minimal and so the water can be considered a one-time investment for the most part. There are plenty of hills around here and so the next question would be What is the optimal height required to turn turbines that can generate the required amount of electricity? The initial investment would probably be somewhere between five and twenty million dollars. So, the next question would be How many years would it take to generate enough revenue to justify the initial investment? Finally, Can the necessary permits be acquired? and Is this method of generating energy more cost-efficient than the available options? Answering all these questions would take a lot of data, but I think those are the basic question which would need to be answered before embarking on a project like this.

cactuspete: Although the question about the necessary permits is an annoyance, I don't think that the permits would be difficult to acquire if a pumped hydro project were financially feasible. I seriously doubt that such a system would be worth the construction costs. Once built it would be a wonderful thing, but it would probably take a century to pay for itself. Having said that, such a system would be extremely clean and so in the long run it might be worth the expense, but it would only have a net positive effect if thousands of such systems were constructed across the country. Even at that, it might not be the BEST solution, although it would definitely be a good solution.

Interesting idea. Even if it isn't the best solution, it would be neat to get some kind of grant to do a pilot project. Pioneer Point is a small community and I'd imagine that the size of the reservoirs needed would not be huge. Plenty of sun for solar here and once the water is in one of the reservoirs and the turbines hooked up, Pioneer Point could be energy independent quite possibly.

CrustyOldFart: Implementing the pumped hydro system in Homewood Canyon would be fairly easy. They have the elevation change and the water. All they would need is pipe which could be laid by the road, the reservoirs, and the generation facility, which wouldn't need to be terribly large. Pioneer Point would be much more of a challenge. I think the BLM would be a major obstacle in Homewood Canyon and the permits for a large project would probably be impossible to obtain.

This is an interesting idea. It would be quite an accomplishment to make a community such as Pioneer Point completely self-sufficient in terms of energy generation and water supply. It can be done. We have the technology! Not sure if it could be done for a mere SIX MILLION DOLLARS though.